A $51.4bn capex bill: the week Wall Street turned on AI spending

Through Wednesday's close the S&P 500 was up 1.6% on the week and Wall Street had just logged a three-day winning streak. Then Alphabet published a capital expenditure figure — $51.4bn for a single quarter, more than double the $24.0bn it spent a year earlier — and the week turned inside out. The index ended Thursday up 1.3% on the week instead, and by early Friday afternoon in New York it was giving back most of what was left.

That is the week in one number, and it is worth being precise about what actually changed. Nothing in the economic data broke. The Federal Reserve did what our Monday note said futures were pricing and held its target range at 3.75%-4%. Third-quarter GDP came in at an annualised 3.4%, up from 2.2% in the second quarter and ahead of forecasts. What broke was the market's willingness to treat AI capital spending as automatically good news. For most of this year, a hyperscaler announcing a bigger build-out was rewarded for it. This week three of them announced bigger build-outs and were punished.

One note on timing. We publish at 18:00 UK time, which is 13:00 in New York, and the US session does not close until 16:00 ET — 20:00 in London. Monday to Thursday below are finished sessions reported at their closing levels. Friday is still trading as this is written, so it appears only as intraday direction.

How the week unfolded

The sentiment we logged each morning tells the arc on its own: Risk-on on Monday, Mixed on Tuesday, Wednesday and Thursday, Risk-off on Friday. A week that opened with buyers in control is closing with them in retreat.

Monday was the AI trade at its most confident. Oil retreated more than 1% after President Trump ruled out a strike on Iran, and Anthropic's confidential filing for a stock market listing — reportedly showing $16.3bn of revenue for the six months to June — reignited the theme after a bruising previous week. The S&P 500 closed at 7,676.77, up 0.70%; the Nasdaq Composite at 26,169.38, up 0.82%; the Dow Jones Industrial Average at 52,361.58, up 0.28%.

Tuesday extended the move, but narrowly. The S&P 500 added 0.6% to 7,722.60 and the Nasdaq rose 1.2% to 26,477.81, while the Dow managed just 15.99 points — less than 0.1% — to 52,377.57, held back by Boeing. That split is the week in miniature: the index with the heaviest technology weighting was doing all the work.

Wednesday brought the catalyst we flagged on Monday, and it landed quietly. The Fed held at 3.75%-4% in a 10-2 vote and markets took it calmly, the S&P 500 rising 0.3% to 7,743.98, the Nasdaq 0.3% to 26,549.85 and the Dow 0.2% to 52,475.10. But the two dissents ran the opposite way to what a British reader might assume. Governor Lisa Cook and Cleveland Fed President Beth Hammack both wanted rates a quarter point higher, not lower. American policy language is worth decoding here: a "hawkish hold" means the committee did not move but signalled it is more worried about inflation than about growth. Immediately after the decision, CME's FedWatch tool put the implied probability of a December increase at 82.6%.

Then Wednesday evening did the damage. Alphabet and Microsoft reported after the closing bell — the US convention is that large companies publish results outside market hours, so the share price reaction lands in the following morning's session rather than the same day's. Alphabet's revenue was fine and Google Cloud more than doubled to $30.7bn. The problem was cash: that $51.4bn of quarterly capital spending pushed free cash flow to roughly negative $9.1bn, and the company held full-year capex guidance at $195bn-$205bn. Microsoft told the opposite story. Azure cloud revenue grew 48% against a consensus nearer 44%, with guidance of around 49% for the current quarter, and capital spending of $45.2bn came in below the roughly $51bn expected.

Thursday priced that split. Alphabet fell about 12.6%, its worst earnings-day reaction on record, while Microsoft rose. The same morning, the Commerce Department's advance estimate put third-quarter growth at 3.4% annualised, and September's personal consumption expenditures index — the Fed's preferred inflation gauge — rose to 3.6% year on year from 3.4%, with the core measure at 3.1%. Solid growth alongside firmer inflation is precisely the combination that keeps a December increase live. The S&P 500 fell 23.59 points, or 0.3%, to 7,720.39; the Nasdaq dropped 365.13 points, or 1.4%, to 26,184.72; the Dow fell 132.54 points, or 0.3%, to 52,342.56. The detail that matters most: the Russell 2000 index of smaller US companies rose 1% to 2,859.22 the same day. This was never a market-wide sell-off.

Friday's session is still open as this is published. Amazon and Intel both reported after Thursday's close and both disappointed, and in early-afternoon New York trading the Nasdaq Composite is down roughly 2.5%, the S&P 500 about 1.5% and the Dow around 0.6%. Those are intraday readings from a session with three hours left to run; the closing levels do not exist yet.

The names that moved it

Alphabet carried this week, in the wrong direction. The roughly 12.6% Thursday fall took close to $400bn off its market value, and it did so on a quarter in which the operating business grew strongly. Investors objected to the bill, not the business.

Microsoft was the counter-example, and the pairing is what makes the week legible: the same AI spending story, received very differently depending on whether cash generation held up alongside it. Microsoft also trimmed its full-year capital spending forecast, to about $170bn from $175bn.

Amazon closed the hyperscaler run on Thursday evening with third-quarter revenue of $201.9bn, up 12% on the year, but adjusted earnings of $1.89 a share against a $1.96 forecast. What moved the stock was the guide to $220bn of 2026 capital spending, set against trailing-12-month free cash flow of negative $42.4bn.

Intel produced the single largest move of the week, and not for the reason its headline numbers suggest. It beat on both lines, with data-centre revenue up 78% to $7.3bn, its strongest growth in 15 years. But fourth-quarter guidance of $0.25 a share against $0.43 expected, on revenue of $15.0bn-$16.0bn, sent the shares down roughly 29% in Friday afternoon trading — a decline that would rank as the company's worst single day since 1974 if it holds to the close.

Away from technology the week read quite differently, which is rather the point. Boeing reported a record $745bn order backlog on Tuesday after the FAA granted amended type certification to its 737-7. GE Vernova beat on Wednesday with adjusted earnings of $4.81 a share against a $4.00 consensus and revenue of $12.64bn, raised 2026 revenue guidance to $46.5bn-$47.5bn and lifted its buyback authorisation to $20bn. On Friday, Exxon Mobil earned an adjusted $4.23 a share and announced a $20bn buyback for 2027, while Chevron earned $5.06 a share on revenue up 36% to $67.8bn; both traded higher as the technology complex fell. Our Wednesday note had also flagged the memory read-through from SK Hynix's 632% profit surge, which lifted Micron and SanDisk more than 4% that morning — a useful marker of how hard the AI trade was still running at mid-week. Every figure in this section is in US dollars.

What to watch next week

Third-quarter earnings season runs on. Roughly 160 S&P 500 companies reported in this week alone and the calendar is not finished. Weekly US jobless claims are due on Thursday at 8:30am ET, which is 13:30 UK time from next week, as American clocks go back on 1 November and the gap between London and New York returns to five hours.

The larger scheduled item sits further out. The Fed's December policy meeting is the one this week's data and dissents have put in focus, with market-implied pricing at an 82.6% chance of a quarter-point increase straight after Wednesday's decision. The Bureau of Economic Analysis publishes its second estimate of third-quarter GDP on 25 November. The names discussed above can be screened on our screener.